This two-digit digital pressure gauge was found in the 1992 special edition of Radio Electronics Experimenter. A/D converter integrated circuits are uncommon today.
This circuit is from a Radio Electronics magazine from December 1971. The resistors are power...
This general purpose circuit was found in a Popular Electronics. It is intended for detecting the...
This circuit produces a tone by a small loudspeaker. Frequency depends on C1 and C2. These...